commit 58f423fbd5f7f435e8dc56dfa565b043d20d1e1b
author Kevin Wolf <kwolf@redhat.com> Wed Jul 09 19:17:30 2014 +0200
committer Kevin Wolf <kwolf@redhat.com> Mon Jul 14 12:03:21 2014 +0200
tree 7d9178c0b85596d3ea4b2565ce1054e8213ce423
parent 80504dcaa11097b99842312014f5954a54fe1826

dma-helpers: Fix too long qiov

If the size of the scatter/gather list isn't a multiple of 512, the
number of sectors for the block layer request is rounded down, resulting
in a qiov that doesn't match the request length. Truncate the qiov to the
new length of the request.

This fixes the IDE qtest case /x86_64/ide/bmdma/short_prdt.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

dma-helpers.c

diff --git a/dma-helpers.c b/dma-helpers.c
index 53cbe92..499b52b 100644
--- a/dma-helpers.c
+++ b/dma-helpers.c
@@ -170,6 +170,10 @@
         return;
     }
 
+    if (dbs->iov.size & ~BDRV_SECTOR_MASK) {
+        qemu_iovec_discard_back(&dbs->iov, dbs->iov.size & ~BDRV_SECTOR_MASK);
+    }
+
     dbs->acb = dbs->io_func(dbs->bs, dbs->sector_num, &dbs->iov,
                             dbs->iov.size / 512, dma_bdrv_cb, dbs);
     assert(dbs->acb);